Valve collision problem |
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Valve collision problem |
thomasotten |
Jun 30 2018, 08:03 PM
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#1
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Senior Member Group: Members Posts: 1,544 Joined: 16-November 03 From: San Antonio, Texas Member No.: 1,349 |
I am having a bit of a problem with my latest 2 liter build. Basically, valves are colliding with pistons after warm up during break in. A valve got stuck and the pushrod actually fell off the rocker.
The heads were redon by RIMCO. After the problem happened, I pulled the heads, and there was clear indication of valve collision, and I had a valve stuck open. The head with a problem was sent back to RIMCO. Reinstalled. What happened this time is the engine start up from cold, runs fine. But then I can hear the taping of collision again. The taping is accompanied by a chirping sound that sounds like something is dragging. I think it must be the valves dragging and closing too slow. I have a deck height of .065. This is essentially a stock build, stock camshaft, etc. Any ideas? Is this perhaps a valve stem lubrication issue? |
Mark Henry |
Jul 1 2018, 08:31 AM
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#2
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Possible causes:
Guides not sized/reamed/honed correctly after install, guides tight, valves sticking. Since you are saying it happens after warm up this is suspect. If this is the issue if you remove the springs you should feel drag on the valve even cold. I agree bent valve, but they usually bend at the tulip, not the stem. Done right the valve should have no drag or sticky spots, it should slip like it's running in butter. Same vein, when driving the guides in the tool is leaving a burr at the top (spring side) of the guide, again this is not sized/reamed/honed correctly after install issue. Cam gear off by one tooth. Lifter sticking in bore, unlikely but possible. Bad or broken spring, weak spring should only show up in higher RPM's Chirping sound, a fast squeak-squeak-squeak can also be a head sealing issue but you should be able to see (head off) carbon tracing or if using head gaskets a definite damage to the gasket. In extreme cases this will cut right into the aluminum head like a cutting torch. |
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